Oxide perovskites have emerged as an important class of materials with important applications in many technological areas, particularly thermocatalysis, electrocatalysis, photocatalysis, and energy storage. However, their implementation faces numerous challenges that are familiar to the chemist and materials scientist. The present work surveys the state-of-the-art by integrating these two viewpoints, focusing on the critical role that defect engineering plays in the design, fabrication, modification, and application of these materials. An extensive review of experimental and simulation studies of the synthesis and performance of oxide perovskites and devices containing these materials is coupled with exposition of the fundamental and applied aspects of defect equilibria. The aim of this approach is to elucidate how these issues can be integrated in order to shed light on the interpretation of the data and what trajectories are suggested by them. This critical examination has revealed a number of areas in which the review can provide a greater understanding. These include considerations of (1) the nature and formation of solid solutions, (2) site filling and stoichiometry, (3) the rationale for the design of defective oxide perovskites, and (4) the complex mechanisms of charge compensation and charge transfer. The review concludes with some proposed strategies to address the challenges in the future development of oxide perovskites and their applications.

Defect engineering of oxide perovskites for catalysis and energy storage: synthesis of chemistry and materials science.

Perovskite Oxide Catalysts for Advanced Oxidation Reactions

Electrochemical capacitors charge and discharge more rapidly than batteries over longer cycles, but their practical applications remain limited due to their significantly lower energy densities. Pseudocapacitors and hybrid capacitors have been developed to extend Ragone plots to higher energy density values, but they are also limited by the insufficient breadth of options for electrode materials, which require materials that store alkali metal cations such as Li+ and Na+. Herein, we report a comprehensive and systematic review of emerging anion storage materials for performance- and functionality-oriented applications in electrochemical and battery-capacitor hybrid devices. The operating principles and types of dual-ion and whole-anion storage in electrochemical and hybrid capacitors are addressed along with the classification, thermodynamic and kinetic aspects, and associated interfaces of anion storage materials in various aqueous and non-aqueous electrolytes. The charge storage mechanism, structure-property correlation, and electrochemical features of anion storage materials are comprehensively discussed. The recent progress in emerging anion storage materials is also discussed, focusing on high-performance applications, such as dual-ion- and whole-anion-storing electrochemical capacitors in a symmetric or hybrid manner, and functional applications including micro- and flexible capacitors, desalination, and salinity cells. Finally, we present our perspective on the current impediments and future directions in this field.

Emerging trends in anion storage materials for the capacitive and hybrid energy storage and beyond.

Double perovskite La2CoMnO6 hollow spheres prepared by template impregnation for high-performance supercapacitors

Oxygen vacancy (V) is one of the most common defects in metal oxides (MOs), which endow the MOs with many unique physiochemical properties. Even though V engineering has been applied in photo(electro)catalysis, there are still significant challenges in the understanding of the formation, structure, and property of V. The V can be produced by treating MOs under low oxygen atmosphere or in vacuum ruled by the equilibrium of V formation, while other types of defects can also be generated simultaneously. Identifying and distinguishing the formation and function of Vo remain highly challenging, thus the scrutiny of defect formation energy and structure of V is significant in V research. This review critically revisits the electronic property and structure changes of MOs upon the generation of Vo. It not only provides clues to detect V, but also specifies the role of V in a particular material system considering its drastic influence on light harvesting, conductivity, energy level, surface adsorption, and others. The review also presents a perspective on the future research directions toward rational control of the key aspects of Vo in MOs, namely its formation, characterization, and function, for solar energy conversion.

Formation, Detection, and Function of Oxygen Vacancy in Metal Oxides for Solar Energy Conversion

The content of oxygen vacancy, as the intercalation places of oxygen during the oxygen ion intercalation process, has a significant influence on the electrochemical properties of the perovskite pse...

Facile Synthesis of LaCoO3 with a High Oxygen Vacancy Concentration by the Plasma Etching Technique for High-Performance Oxygen Ion Intercalation Pseudocapacitors

Facile synthesis of heterogeneous Co3O4-nanowires/vertical-graphene-nanosheets on Ni foam for high performance supercapacitors

The development of aerogel materials with high preparation efficiency, no pollution, and high adsorption efficiency was still an effective solution for water pollution caused by heavy metal ions. This paper...

Characterization and evaluation of adsorption potential of chitosan impregnated cellulose nanofiber / multi-walled carbon nanotubes aerogel for copper ions

The invention discloses an asymmetric capacitor based on lanthanum cobaltate and graphene oxide and a preparation method thereof. The capacitor comprises a positive pole piece, a negative pole piece,an organic electrolyte and a diaphragm, wherein the positive pole piece is composed of a current collector and a positive pole material coating the surface of the current collector, and the positive pole material comprises lanthanum cobaltate, acetylene black and polyvinylidene fluoride; the negative pole piece is composed of a current collector and a negative pole material coating the surface ofthe current collector, and the negative pole material comprises graphene oxide; and the organic electrolyte is a 4 to 6M potassium hydroxide solution. The asymmetric capacitor has excellent electrochemical performance, the specific capacitance value of 134 F/g is shown under the current density of 1 A/g, the current density is increased to 50 A/g, the specific capacitance can still be kept at 98.5F/g, and the capacitance retention rate is 73.5%; an energy density-power density test result shows that the capacitance performance is good; cyclic test results show that the energy conversion rateof charging and discharging is high.

Kang Ouyang

Papers

Facile Synthesis of LaCoO3 with a High Oxygen Vacancy Concentration by the Plasma Etching Technique for High-Performance Oxygen Ion Intercalation Pseudocapacitors

Facile synthesis of heterogeneous Co3O4-nanowires/vertical-graphene-nanosheets on Ni foam for high performance supercapacitors

Characterization and evaluation of adsorption potential of chitosan impregnated cellulose nanofiber / multi-walled carbon nanotubes aerogel for copper ions

Asymmetric capacitor based on lanthanum cobaltate and graphene oxide and preparation method thereof